[GHC] #10491: Regression, simplifier explosion with Accelerate, cannot compile, increasing tick factor is not a workaround

[GHC]

#10491: Regression, simplifier explosion with Accelerate, cannot compile,
increasing tick factor is not a workaround
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        Reporter:  robertce          |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  highest           |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by bgamari):

 George, what GHC version did you test `-fno-specialise` on? While
 yesterday I was able to confirm that `-fno-specialise` seemed to make no
 difference on a test machine running what should have been 7.10.1 I am now
 having trouble replicating this on my laptop. Unfortunately I no longer
 have access to the test environment on which I tested this yesterday but
 clearly something was inconsistent.

 I am now seeing on multiple machines that `-fno-specialise` indeed allows
 things to compile,
 {{{
 $ ghc -V
 The Glorious Glasgow Haskell Compilation System, version 7.10.1
 $$ time ghc Slice.hs -fforce-recomp -O2 -fno-specialise
 [1 of 1] Compiling Slice            ( Slice.hs, Slice.o )

 real    0m3.759s
 user    0m1.688s
 sys     0m0.044s
 $ time ghc Slice.hs -fforce-recomp -O2
 [1 of 1] Compiling Slice            ( Slice.hs, Slice.o )
 ^C

 real    0m51.103s
 user    0m44.336s
 sys     0m0.948s
 }}}

 I am now looking at whether disabling only cross-module specialisation is
 enough to eliminate the blow-up.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10491#comment:27>
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